The present invention relates to a machine for the preparation of beverages and, in particular, for use with sealed cartridges which are formed from substantially air-and water-impermeable materials and which contain one or more ingredients for the preparation of beverages.
It has previously been proposed to seal beverage preparation ingredients in individual air-impermeable packages for use in beverage machines. For example, cartridges or capsules containing compacted ground coffee are known for use in certain coffee preparation machines which are generally termed “espresso” machines. In the production of coffee using these preparation machines the coffee cartridge is placed in a brewing chamber and hot water is passed though the cartridge at relatively high pressures, thereby extracting the aromatic coffee constituents from the ground coffee to produce the coffee beverage. Typically, such machines operate at a pressure of greater than 6×105 Pa. The preparation machines of the type described have to date been relatively expensive since components of the machine, such as the water pumps and seals, must be able to withstand the high pressures.
In WO01/58786 there is described a cartridge for the preparation of beverages which operates at a pressure generally in the range 0.7 to 2.0×105 Pa. However, the cartridge is designed for use in a beverage preparation machine for the commercial or industrial market and is relatively expensive. Hence, there remains a requirement for a cartridge for the preparation of beverages wherein the cartridges and beverage preparation machine are suitable, in particular, for the domestic market in terms of cost, performance and reliability. There is also a need for a beverage preparation machine for such cartridges which is simple to operate and reliable in operation. In particular, means are required to provide a reliable and known sealing force to withstand pressure within the beverage cartridge during a dispense cycle.